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Understanding Chromosomes: DNA Reproduction in Cells

Explore the world of DNA, chromosomes, and cell reproduction. Discover the role of DNA in storing genetic information and how chromosomes shape our genetic makeup. Learn about chromatids, centromeres, and the fascinating process of cell division.

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Understanding Chromosomes: DNA Reproduction in Cells

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Presentation Transcript

  1. Cell Reproduction

  2. DNA • Stands for deoxyribonucleic acid • Function is to store genetic information • ~3 billion nucleotides in human cells • Bases are abbreviated A, T, C, G • These are coiled and packed tightly into a double helix

  3. Chromosomes • Rod-shaped structures made of DNA and proteins • DNA is tightlywound • Humans have 46 chromosomes, other animals have different numbers

  4. Chromatid • Half of a chromosome • Looks like a pipe cleaner

  5. Centromere • Binds two chromatids together • Like a rubber band

  6. Review • A chromosome… • …is made up of two chromatids… • …held together by a centromere

  7. Chromatin • Loose coils of DNA • Occurs in cells during normal cell function • This allows information to be read

  8. Prokaryotes vs Eukaryotes • Chromosomes are simpler in prokaryotes than eukaryotes • Prokaryotes have circular DNA • Eukaryotes have double-helix shaped DNA

  9. Chromosome Numbers • The number of chromosomes an organism has does not indicate how complex it is

  10. Sex Chromosomes • Main function is to determine gender of an organism • In humans • XX is female • XY is male • Only 2 of the 46 human chromosomes are sex chromosomes

  11. Sex Chromosomes • A person with… XY XX

  12. Autosomes • All other chromosomes besides sex chromosomes • 44 of the 46 human chromosomes are autosomes

  13. Homologous Pairs • Chromosomes with the same… • Size • Shape • Genes • Organisms receive one copy from each parent • Chromosomes have similar genes, even though they may have different instructions • Eye color, hair color, etc.

  14. Karyotype • Picture of chromosomes in a normal human cell • 22 pairs of autosomes and 1 pair of sex chromosomes (46 total chromosomes)

  15. Diploid Cells (2n) • “Di-” - two • All cells except sex cells are diploid • 2 autosomes per homologous pair • 2n number in humans is 46 • 44 autosomes • 2 sex chromosomes

  16. Haploid Cells (1n) • “Hap-” – single • (sounds like “half”) • Only sex cells are haploid • 1 autosome per homologous pair • 1n number in humans is 23 • 22 autosomes • 1 sex chromosome

  17. Diploid or Haploid Cell? • Diploid • Haploid Did the haploid cell come from a male or a female?

  18. Complete the table and list the diploid and haploid number of chromosomes

  19. What organelle do is directly related to cell division? • Do males or females determine the sex of a baby? • True or False- Every human cell contains 46 chromosomes. • Because orangutans have 48 chromosomes, does that mean they are more highly evolved than humans? Why? • True or False- Haploid cells only have one chromosome • Why must sex cells be haploid?

  20. Complete the table and list the diploid and haploid number of chromosomes

  21. Lab Vocab • Deletion • Portion of the chromosome is lost • Duplication • The deletion becomes incorporated into its homologue so that the segment appears twice on the same chromosome • Translocation • The deleted portion is transferred to a chromosome other than its homologue

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